1. Field of the Invention
The present invention relates to a printer and printing method capable of double-sided printing. More particularly, the present invention relates to a printer and printing method in which images are printed to two surfaces of a recording sheet after loading of the recording sheet for two times, and a combination of the images can be correct in a print without an error.
2. Description Related to the Prior Art
A general type of a printer is normally operated to print an image to one recording surface at one time, but can be used for double-sided printing in which a first image is printed to one front surface of a recording sheet, and then a second image is printed to its rear surface after turning over the recording sheet. For reliability in the operation of the double-sided printing, it is important to set an orientation of the recording sheet for a recording head direction of the printer at the time of printing to the rear surface, and also to check an image to be printed to the rear surface of the recording sheet in an exact combination with the image printed to the front surface.
JP-A 5-011529 discloses the printer of which a printer body is provided with an indicator panel, which indicates a placing orientation of the recording sheet at the time of printing to the rear surface, and information of a feeding order of the recording sheet. This prevents errors in double printing to the front surface, and prevents errors in the combination of an original images between the front and rear surfaces. JP-A 2000-094783 discloses the printer in which a discrimination indicia is printed at the time of printing to the front surface for the purpose of recording information of associating the original image of the front surface with the original image of the rear surface. Also, the printer records a direction indicia for recognizing a feeding direction of the recording sheet. At the time of printing to the rear surface, a reading sensor reads the direction indicia or the discrimination indicia, to estimate the feeding direction of the recording sheet. Only when the recording sheet has the discrimination indicia associated with the original image, an image is printed to the rear surface. This is to combine the original images without fail between the front and rear surfaces.
In the printer of JP-A 5-011529, the indicator panel only shows information that the front surface of the recording sheet should be oriented upwards or downwards after the front printing. As an instruction of the feeding direction is not indicated, an error is likely to occur in a printing direction between the front and rear surfaces according to an error in the feeding direction of the recording sheet. Also, if there is an error in the sequence of feeding of the recording sheets, inconsistency occurs in the original images between the front and rear surfaces. Also, the printer of JP-A 2000-094783 automatically ejects the recording sheet if the feeding direction of the recording sheet is wrong at the time of printing to the rear surface, or if the recording sheet being supplied is unsuitable for the original image of the rear surface. Problems arise in that waste time is considerably long and that processing cannot be quick specifically when the feeding direction of a stack of the recording sheets in a great number is wrong, or when a sequence of supply of the recording sheets is wrong.
In view of the foregoing problems, an object of the present invention is to provide a printer in which images are printed to two surfaces of a recording sheet, and a combination of the images can be correctly determined with great ease in relation to orientation and direction of the front and rear surfaces without an error.
In order to achieve the above and other objects and advantages of this invention, a printer includes an image forming section for printing an image on one of first and second surfaces of a recording sheet oriented in a recordable orientation. A feeder feeds the recording sheet to the image forming section after the recording sheet is set in a sheet supply section. The printer includes at least one first memory for storing first image data of an image for being printed on the first surface, and second image data of an image for being printed on the second surface, the first or second image data being read from the first memory, and input to the image forming section. A second memory stores discrimination information adapted for designating the second image data associated with the first image data according to common assignment to the recording sheet, wherein the discrimination information is read from the second memory at a time of printing with the first image data to the first surface, and is printed on the first surface by the image forming section. A first reader reads the discrimination information from the first surface at a time of printing to the second surface, the second image data being specified according to the discrimination information, read from the first memory, and input to the image forming section.
The image forming section prints a positioning pointer on the first surface at the printing time to the first surface, the positioning pointer being adapted for positioning the recording sheet when the recording sheet is set in the sheet supply section for printing to the second surface.
Furthermore, a second reader reads sheet type information prerecorded on the second surface, the first image data being specified according to the sheet type information, and subjected to printing on the first surface.
The discrimination information, the positioning pointer and the sheet type information are recorded on an advancing edge portion of the recording sheet.
The image forming section includes a thermal head for printing to the recording sheet being thermosensitive. A platen roller is disposed higher than the thermal head, for supporting the recording sheet.
The recordable orientation is a downward orientation.
The discrimination information is formed in an edge portion of the recording sheet, and has a patterned shape determined by encoding two-surface combining information.
Furthermore, a sheet supply slot receives the recording sheet set therein, to supply the recording sheet to the image forming section. A target pointer is disposed at the sheet supply slot, and so positioned that the positioning pointer becomes opposed thereto when the recording sheet is turned over and reloaded.
The sheet type information is formed in an edge portion of the second surface, and has a patterned shape determined by encoding a type of the recording sheet, and the second reader is constituted by the first reader.
According to another aspect of the invention, a printing method of printing an image on a first surface of a recording sheet, and serially an image on a second surface of the recording sheet, is provided. At first, the recording sheet is set in a sheet supply section in orienting the first surface in a recordable orientation. The recording sheet is fed to an image forming section. An image is printed on the first surface with the image forming section according to first image data, then the recording sheet being exited to a sheet exit section. In the printing step to the first surface, a positioning pointer is printed on the first surface for designating a position of the recording sheet. After the printing step to the first surface, the recording sheet is set in the sheet supply section in setting the positioning pointer at a target pointer of the sheet supply section, the second surface being oriented in the recordable orientation. The recording sheet is fed to the image forming section. An image is printed on the second surface with the image forming section according to the second image data, then the recording sheet being exited to the sheet exit section.